1//
2// posix/basic_descriptor.hpp
3// ~~~~~~~~~~~~~~~~~~~~~~~~~~
4//
5// Copyright (c) 2003-2024 Christopher M. Kohlhoff (chris at kohlhoff dot com)
6//
7// Distributed under the Boost Software License, Version 1.0. (See accompanying
8// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
9//
10
11#ifndef BOOST_ASIO_POSIX_BASIC_DESCRIPTOR_HPP
12#define BOOST_ASIO_POSIX_BASIC_DESCRIPTOR_HPP
13
14#if defined(_MSC_VER) && (_MSC_VER >= 1200)
15# pragma once
16#endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
17
18#include <boost/asio/detail/config.hpp>
19
20#if defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR) \
21 || defined(GENERATING_DOCUMENTATION)
22
23#include <utility>
24#include <boost/asio/any_io_executor.hpp>
25#include <boost/asio/async_result.hpp>
26#include <boost/asio/detail/handler_type_requirements.hpp>
27#include <boost/asio/detail/io_object_impl.hpp>
28#include <boost/asio/detail/non_const_lvalue.hpp>
29#include <boost/asio/detail/throw_error.hpp>
30#include <boost/asio/error.hpp>
31#include <boost/asio/execution_context.hpp>
32#include <boost/asio/posix/descriptor_base.hpp>
33
34#if defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
35# include <boost/asio/detail/io_uring_descriptor_service.hpp>
36#else // defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
37# include <boost/asio/detail/reactive_descriptor_service.hpp>
38#endif // defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
39
40#include <boost/asio/detail/push_options.hpp>
41
42namespace boost {
43namespace asio {
44namespace posix {
45
46/// Provides POSIX descriptor functionality.
47/**
48 * The posix::basic_descriptor class template provides the ability to wrap a
49 * POSIX descriptor.
50 *
51 * @par Thread Safety
52 * @e Distinct @e objects: Safe.@n
53 * @e Shared @e objects: Unsafe.
54 */
55template <typename Executor = any_io_executor>
56class basic_descriptor
57 : public descriptor_base
58{
59private:
60 class initiate_async_wait;
61
62public:
63 /// The type of the executor associated with the object.
64 typedef Executor executor_type;
65
66 /// Rebinds the descriptor type to another executor.
67 template <typename Executor1>
68 struct rebind_executor
69 {
70 /// The descriptor type when rebound to the specified executor.
71 typedef basic_descriptor<Executor1> other;
72 };
73
74 /// The native representation of a descriptor.
75#if defined(GENERATING_DOCUMENTATION)
76 typedef implementation_defined native_handle_type;
77#elif defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
78 typedef detail::io_uring_descriptor_service::native_handle_type
79 native_handle_type;
80#else // defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
81 typedef detail::reactive_descriptor_service::native_handle_type
82 native_handle_type;
83#endif // defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
84
85 /// A descriptor is always the lowest layer.
86 typedef basic_descriptor lowest_layer_type;
87
88 /// Construct a descriptor without opening it.
89 /**
90 * This constructor creates a descriptor without opening it.
91 *
92 * @param ex The I/O executor that the descriptor will use, by default, to
93 * dispatch handlers for any asynchronous operations performed on the
94 * descriptor.
95 */
96 explicit basic_descriptor(const executor_type& ex)
97 : impl_(0, ex)
98 {
99 }
100
101 /// Construct a descriptor without opening it.
102 /**
103 * This constructor creates a descriptor without opening it.
104 *
105 * @param context An execution context which provides the I/O executor that
106 * the descriptor will use, by default, to dispatch handlers for any
107 * asynchronous operations performed on the descriptor.
108 */
109 template <typename ExecutionContext>
110 explicit basic_descriptor(ExecutionContext& context,
111 constraint_t<
112 is_convertible<ExecutionContext&, execution_context&>::value,
113 defaulted_constraint
114 > = defaulted_constraint())
115 : impl_(0, 0, context)
116 {
117 }
118
119 /// Construct a descriptor on an existing native descriptor.
120 /**
121 * This constructor creates a descriptor object to hold an existing native
122 * descriptor.
123 *
124 * @param ex The I/O executor that the descriptor will use, by default, to
125 * dispatch handlers for any asynchronous operations performed on the
126 * descriptor.
127 *
128 * @param native_descriptor A native descriptor.
129 *
130 * @throws boost::system::system_error Thrown on failure.
131 */
132 basic_descriptor(const executor_type& ex,
133 const native_handle_type& native_descriptor)
134 : impl_(0, ex)
135 {
136 boost::system::error_code ec;
137 impl_.get_service().assign(impl_.get_implementation(),
138 native_descriptor, ec);
139 boost::asio::detail::throw_error(err: ec, location: "assign");
140 }
141
142 /// Construct a descriptor on an existing native descriptor.
143 /**
144 * This constructor creates a descriptor object to hold an existing native
145 * descriptor.
146 *
147 * @param context An execution context which provides the I/O executor that
148 * the descriptor will use, by default, to dispatch handlers for any
149 * asynchronous operations performed on the descriptor.
150 *
151 * @param native_descriptor A native descriptor.
152 *
153 * @throws boost::system::system_error Thrown on failure.
154 */
155 template <typename ExecutionContext>
156 basic_descriptor(ExecutionContext& context,
157 const native_handle_type& native_descriptor,
158 constraint_t<
159 is_convertible<ExecutionContext&, execution_context&>::value
160 > = 0)
161 : impl_(0, 0, context)
162 {
163 boost::system::error_code ec;
164 impl_.get_service().assign(impl_.get_implementation(),
165 native_descriptor, ec);
166 boost::asio::detail::throw_error(err: ec, location: "assign");
167 }
168
169 /// Move-construct a descriptor from another.
170 /**
171 * This constructor moves a descriptor from one object to another.
172 *
173 * @param other The other descriptor object from which the move will
174 * occur.
175 *
176 * @note Following the move, the moved-from object is in the same state as if
177 * constructed using the @c basic_descriptor(const executor_type&)
178 * constructor.
179 */
180 basic_descriptor(basic_descriptor&& other) noexcept
181 : impl_(std::move(other.impl_))
182 {
183 }
184
185 /// Move-assign a descriptor from another.
186 /**
187 * This assignment operator moves a descriptor from one object to another.
188 *
189 * @param other The other descriptor object from which the move will
190 * occur.
191 *
192 * @note Following the move, the moved-from object is in the same state as if
193 * constructed using the @c basic_descriptor(const executor_type&)
194 * constructor.
195 */
196 basic_descriptor& operator=(basic_descriptor&& other)
197 {
198 impl_ = std::move(other.impl_);
199 return *this;
200 }
201
202 // All descriptors have access to each other's implementations.
203 template <typename Executor1>
204 friend class basic_descriptor;
205
206 /// Move-construct a basic_descriptor from a descriptor of another executor
207 /// type.
208 /**
209 * This constructor moves a descriptor from one object to another.
210 *
211 * @param other The other basic_descriptor object from which the move will
212 * occur.
213 *
214 * @note Following the move, the moved-from object is in the same state as if
215 * constructed using the @c basic_descriptor(const executor_type&)
216 * constructor.
217 */
218 template <typename Executor1>
219 basic_descriptor(basic_descriptor<Executor1>&& other,
220 constraint_t<
221 is_convertible<Executor1, Executor>::value,
222 defaulted_constraint
223 > = defaulted_constraint())
224 : impl_(std::move(other.impl_))
225 {
226 }
227
228 /// Move-assign a basic_descriptor from a descriptor of another executor type.
229 /**
230 * This assignment operator moves a descriptor from one object to another.
231 *
232 * @param other The other basic_descriptor object from which the move will
233 * occur.
234 *
235 * @note Following the move, the moved-from object is in the same state as if
236 * constructed using the @c basic_descriptor(const executor_type&)
237 * constructor.
238 */
239 template <typename Executor1>
240 constraint_t<
241 is_convertible<Executor1, Executor>::value,
242 basic_descriptor&
243 > operator=(basic_descriptor<Executor1> && other)
244 {
245 basic_descriptor tmp(std::move(other));
246 impl_ = std::move(tmp.impl_);
247 return *this;
248 }
249
250 /// Get the executor associated with the object.
251 const executor_type& get_executor() noexcept
252 {
253 return impl_.get_executor();
254 }
255
256 /// Get a reference to the lowest layer.
257 /**
258 * This function returns a reference to the lowest layer in a stack of
259 * layers. Since a descriptor cannot contain any further layers, it
260 * simply returns a reference to itself.
261 *
262 * @return A reference to the lowest layer in the stack of layers. Ownership
263 * is not transferred to the caller.
264 */
265 lowest_layer_type& lowest_layer()
266 {
267 return *this;
268 }
269
270 /// Get a const reference to the lowest layer.
271 /**
272 * This function returns a const reference to the lowest layer in a stack of
273 * layers. Since a descriptor cannot contain any further layers, it
274 * simply returns a reference to itself.
275 *
276 * @return A const reference to the lowest layer in the stack of layers.
277 * Ownership is not transferred to the caller.
278 */
279 const lowest_layer_type& lowest_layer() const
280 {
281 return *this;
282 }
283
284 /// Assign an existing native descriptor to the descriptor.
285 /*
286 * This function opens the descriptor to hold an existing native descriptor.
287 *
288 * @param native_descriptor A native descriptor.
289 *
290 * @throws boost::system::system_error Thrown on failure.
291 */
292 void assign(const native_handle_type& native_descriptor)
293 {
294 boost::system::error_code ec;
295 impl_.get_service().assign(impl_.get_implementation(),
296 native_descriptor, ec);
297 boost::asio::detail::throw_error(err: ec, location: "assign");
298 }
299
300 /// Assign an existing native descriptor to the descriptor.
301 /*
302 * This function opens the descriptor to hold an existing native descriptor.
303 *
304 * @param native_descriptor A native descriptor.
305 *
306 * @param ec Set to indicate what error occurred, if any.
307 */
308 BOOST_ASIO_SYNC_OP_VOID assign(const native_handle_type& native_descriptor,
309 boost::system::error_code& ec)
310 {
311 impl_.get_service().assign(
312 impl_.get_implementation(), native_descriptor, ec);
313 BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
314 }
315
316 /// Determine whether the descriptor is open.
317 bool is_open() const
318 {
319 return impl_.get_service().is_open(impl_.get_implementation());
320 }
321
322 /// Close the descriptor.
323 /**
324 * This function is used to close the descriptor. Any asynchronous read or
325 * write operations will be cancelled immediately, and will complete with the
326 * boost::asio::error::operation_aborted error.
327 *
328 * @throws boost::system::system_error Thrown on failure. Note that, even if
329 * the function indicates an error, the underlying descriptor is closed.
330 */
331 void close()
332 {
333 boost::system::error_code ec;
334 impl_.get_service().close(impl_.get_implementation(), ec);
335 boost::asio::detail::throw_error(err: ec, location: "close");
336 }
337
338 /// Close the descriptor.
339 /**
340 * This function is used to close the descriptor. Any asynchronous read or
341 * write operations will be cancelled immediately, and will complete with the
342 * boost::asio::error::operation_aborted error.
343 *
344 * @param ec Set to indicate what error occurred, if any. Note that, even if
345 * the function indicates an error, the underlying descriptor is closed.
346 */
347 BOOST_ASIO_SYNC_OP_VOID close(boost::system::error_code& ec)
348 {
349 impl_.get_service().close(impl_.get_implementation(), ec);
350 BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
351 }
352
353 /// Get the native descriptor representation.
354 /**
355 * This function may be used to obtain the underlying representation of the
356 * descriptor. This is intended to allow access to native descriptor
357 * functionality that is not otherwise provided.
358 */
359 native_handle_type native_handle()
360 {
361 return impl_.get_service().native_handle(impl_.get_implementation());
362 }
363
364 /// Release ownership of the native descriptor implementation.
365 /**
366 * This function may be used to obtain the underlying representation of the
367 * descriptor. After calling this function, @c is_open() returns false. The
368 * caller is responsible for closing the descriptor.
369 *
370 * All outstanding asynchronous read or write operations will finish
371 * immediately, and the handlers for cancelled operations will be passed the
372 * boost::asio::error::operation_aborted error.
373 */
374 native_handle_type release()
375 {
376 return impl_.get_service().release(impl_.get_implementation());
377 }
378
379 /// Cancel all asynchronous operations associated with the descriptor.
380 /**
381 * This function causes all outstanding asynchronous read or write operations
382 * to finish immediately, and the handlers for cancelled operations will be
383 * passed the boost::asio::error::operation_aborted error.
384 *
385 * @throws boost::system::system_error Thrown on failure.
386 */
387 void cancel()
388 {
389 boost::system::error_code ec;
390 impl_.get_service().cancel(impl_.get_implementation(), ec);
391 boost::asio::detail::throw_error(err: ec, location: "cancel");
392 }
393
394 /// Cancel all asynchronous operations associated with the descriptor.
395 /**
396 * This function causes all outstanding asynchronous read or write operations
397 * to finish immediately, and the handlers for cancelled operations will be
398 * passed the boost::asio::error::operation_aborted error.
399 *
400 * @param ec Set to indicate what error occurred, if any.
401 */
402 BOOST_ASIO_SYNC_OP_VOID cancel(boost::system::error_code& ec)
403 {
404 impl_.get_service().cancel(impl_.get_implementation(), ec);
405 BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
406 }
407
408 /// Perform an IO control command on the descriptor.
409 /**
410 * This function is used to execute an IO control command on the descriptor.
411 *
412 * @param command The IO control command to be performed on the descriptor.
413 *
414 * @throws boost::system::system_error Thrown on failure.
415 *
416 * @sa IoControlCommand @n
417 * boost::asio::posix::descriptor_base::bytes_readable @n
418 * boost::asio::posix::descriptor_base::non_blocking_io
419 *
420 * @par Example
421 * Getting the number of bytes ready to read:
422 * @code
423 * boost::asio::posix::stream_descriptor descriptor(my_context);
424 * ...
425 * boost::asio::posix::stream_descriptor::bytes_readable command;
426 * descriptor.io_control(command);
427 * std::size_t bytes_readable = command.get();
428 * @endcode
429 */
430 template <typename IoControlCommand>
431 void io_control(IoControlCommand& command)
432 {
433 boost::system::error_code ec;
434 impl_.get_service().io_control(impl_.get_implementation(), command, ec);
435 boost::asio::detail::throw_error(err: ec, location: "io_control");
436 }
437
438 /// Perform an IO control command on the descriptor.
439 /**
440 * This function is used to execute an IO control command on the descriptor.
441 *
442 * @param command The IO control command to be performed on the descriptor.
443 *
444 * @param ec Set to indicate what error occurred, if any.
445 *
446 * @sa IoControlCommand @n
447 * boost::asio::posix::descriptor_base::bytes_readable @n
448 * boost::asio::posix::descriptor_base::non_blocking_io
449 *
450 * @par Example
451 * Getting the number of bytes ready to read:
452 * @code
453 * boost::asio::posix::stream_descriptor descriptor(my_context);
454 * ...
455 * boost::asio::posix::stream_descriptor::bytes_readable command;
456 * boost::system::error_code ec;
457 * descriptor.io_control(command, ec);
458 * if (ec)
459 * {
460 * // An error occurred.
461 * }
462 * std::size_t bytes_readable = command.get();
463 * @endcode
464 */
465 template <typename IoControlCommand>
466 BOOST_ASIO_SYNC_OP_VOID io_control(IoControlCommand& command,
467 boost::system::error_code& ec)
468 {
469 impl_.get_service().io_control(impl_.get_implementation(), command, ec);
470 BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
471 }
472
473 /// Gets the non-blocking mode of the descriptor.
474 /**
475 * @returns @c true if the descriptor's synchronous operations will fail with
476 * boost::asio::error::would_block if they are unable to perform the requested
477 * operation immediately. If @c false, synchronous operations will block
478 * until complete.
479 *
480 * @note The non-blocking mode has no effect on the behaviour of asynchronous
481 * operations. Asynchronous operations will never fail with the error
482 * boost::asio::error::would_block.
483 */
484 bool non_blocking() const
485 {
486 return impl_.get_service().non_blocking(impl_.get_implementation());
487 }
488
489 /// Sets the non-blocking mode of the descriptor.
490 /**
491 * @param mode If @c true, the descriptor's synchronous operations will fail
492 * with boost::asio::error::would_block if they are unable to perform the
493 * requested operation immediately. If @c false, synchronous operations will
494 * block until complete.
495 *
496 * @throws boost::system::system_error Thrown on failure.
497 *
498 * @note The non-blocking mode has no effect on the behaviour of asynchronous
499 * operations. Asynchronous operations will never fail with the error
500 * boost::asio::error::would_block.
501 */
502 void non_blocking(bool mode)
503 {
504 boost::system::error_code ec;
505 impl_.get_service().non_blocking(impl_.get_implementation(), mode, ec);
506 boost::asio::detail::throw_error(err: ec, location: "non_blocking");
507 }
508
509 /// Sets the non-blocking mode of the descriptor.
510 /**
511 * @param mode If @c true, the descriptor's synchronous operations will fail
512 * with boost::asio::error::would_block if they are unable to perform the
513 * requested operation immediately. If @c false, synchronous operations will
514 * block until complete.
515 *
516 * @param ec Set to indicate what error occurred, if any.
517 *
518 * @note The non-blocking mode has no effect on the behaviour of asynchronous
519 * operations. Asynchronous operations will never fail with the error
520 * boost::asio::error::would_block.
521 */
522 BOOST_ASIO_SYNC_OP_VOID non_blocking(
523 bool mode, boost::system::error_code& ec)
524 {
525 impl_.get_service().non_blocking(impl_.get_implementation(), mode, ec);
526 BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
527 }
528
529 /// Gets the non-blocking mode of the native descriptor implementation.
530 /**
531 * This function is used to retrieve the non-blocking mode of the underlying
532 * native descriptor. This mode has no effect on the behaviour of the
533 * descriptor object's synchronous operations.
534 *
535 * @returns @c true if the underlying descriptor is in non-blocking mode and
536 * direct system calls may fail with boost::asio::error::would_block (or the
537 * equivalent system error).
538 *
539 * @note The current non-blocking mode is cached by the descriptor object.
540 * Consequently, the return value may be incorrect if the non-blocking mode
541 * was set directly on the native descriptor.
542 */
543 bool native_non_blocking() const
544 {
545 return impl_.get_service().native_non_blocking(
546 impl_.get_implementation());
547 }
548
549 /// Sets the non-blocking mode of the native descriptor implementation.
550 /**
551 * This function is used to modify the non-blocking mode of the underlying
552 * native descriptor. It has no effect on the behaviour of the descriptor
553 * object's synchronous operations.
554 *
555 * @param mode If @c true, the underlying descriptor is put into non-blocking
556 * mode and direct system calls may fail with boost::asio::error::would_block
557 * (or the equivalent system error).
558 *
559 * @throws boost::system::system_error Thrown on failure. If the @c mode is
560 * @c false, but the current value of @c non_blocking() is @c true, this
561 * function fails with boost::asio::error::invalid_argument, as the
562 * combination does not make sense.
563 */
564 void native_non_blocking(bool mode)
565 {
566 boost::system::error_code ec;
567 impl_.get_service().native_non_blocking(
568 impl_.get_implementation(), mode, ec);
569 boost::asio::detail::throw_error(err: ec, location: "native_non_blocking");
570 }
571
572 /// Sets the non-blocking mode of the native descriptor implementation.
573 /**
574 * This function is used to modify the non-blocking mode of the underlying
575 * native descriptor. It has no effect on the behaviour of the descriptor
576 * object's synchronous operations.
577 *
578 * @param mode If @c true, the underlying descriptor is put into non-blocking
579 * mode and direct system calls may fail with boost::asio::error::would_block
580 * (or the equivalent system error).
581 *
582 * @param ec Set to indicate what error occurred, if any. If the @c mode is
583 * @c false, but the current value of @c non_blocking() is @c true, this
584 * function fails with boost::asio::error::invalid_argument, as the
585 * combination does not make sense.
586 */
587 BOOST_ASIO_SYNC_OP_VOID native_non_blocking(
588 bool mode, boost::system::error_code& ec)
589 {
590 impl_.get_service().native_non_blocking(
591 impl_.get_implementation(), mode, ec);
592 BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
593 }
594
595 /// Wait for the descriptor to become ready to read, ready to write, or to
596 /// have pending error conditions.
597 /**
598 * This function is used to perform a blocking wait for a descriptor to enter
599 * a ready to read, write or error condition state.
600 *
601 * @param w Specifies the desired descriptor state.
602 *
603 * @par Example
604 * Waiting for a descriptor to become readable.
605 * @code
606 * boost::asio::posix::stream_descriptor descriptor(my_context);
607 * ...
608 * descriptor.wait(boost::asio::posix::stream_descriptor::wait_read);
609 * @endcode
610 */
611 void wait(wait_type w)
612 {
613 boost::system::error_code ec;
614 impl_.get_service().wait(impl_.get_implementation(), w, ec);
615 boost::asio::detail::throw_error(err: ec, location: "wait");
616 }
617
618 /// Wait for the descriptor to become ready to read, ready to write, or to
619 /// have pending error conditions.
620 /**
621 * This function is used to perform a blocking wait for a descriptor to enter
622 * a ready to read, write or error condition state.
623 *
624 * @param w Specifies the desired descriptor state.
625 *
626 * @param ec Set to indicate what error occurred, if any.
627 *
628 * @par Example
629 * Waiting for a descriptor to become readable.
630 * @code
631 * boost::asio::posix::stream_descriptor descriptor(my_context);
632 * ...
633 * boost::system::error_code ec;
634 * descriptor.wait(boost::asio::posix::stream_descriptor::wait_read, ec);
635 * @endcode
636 */
637 BOOST_ASIO_SYNC_OP_VOID wait(wait_type w, boost::system::error_code& ec)
638 {
639 impl_.get_service().wait(impl_.get_implementation(), w, ec);
640 BOOST_ASIO_SYNC_OP_VOID_RETURN(ec);
641 }
642
643 /// Asynchronously wait for the descriptor to become ready to read, ready to
644 /// write, or to have pending error conditions.
645 /**
646 * This function is used to perform an asynchronous wait for a descriptor to
647 * enter a ready to read, write or error condition state. It is an initiating
648 * function for an @ref asynchronous_operation, and always returns
649 * immediately.
650 *
651 * @param w Specifies the desired descriptor state.
652 *
653 * @param token The @ref completion_token that will be used to produce a
654 * completion handler, which will be called when the wait completes.
655 * Potential completion tokens include @ref use_future, @ref use_awaitable,
656 * @ref yield_context, or a function object with the correct completion
657 * signature. The function signature of the completion handler must be:
658 * @code void handler(
659 * const boost::system::error_code& error // Result of operation.
660 * ); @endcode
661 * Regardless of whether the asynchronous operation completes immediately or
662 * not, the completion handler will not be invoked from within this function.
663 * On immediate completion, invocation of the handler will be performed in a
664 * manner equivalent to using boost::asio::post().
665 *
666 * @par Completion Signature
667 * @code void(boost::system::error_code) @endcode
668 *
669 * @par Example
670 * @code
671 * void wait_handler(const boost::system::error_code& error)
672 * {
673 * if (!error)
674 * {
675 * // Wait succeeded.
676 * }
677 * }
678 *
679 * ...
680 *
681 * boost::asio::posix::stream_descriptor descriptor(my_context);
682 * ...
683 * descriptor.async_wait(
684 * boost::asio::posix::stream_descriptor::wait_read,
685 * wait_handler);
686 * @endcode
687 *
688 * @par Per-Operation Cancellation
689 * This asynchronous operation supports cancellation for the following
690 * boost::asio::cancellation_type values:
691 *
692 * @li @c cancellation_type::terminal
693 *
694 * @li @c cancellation_type::partial
695 *
696 * @li @c cancellation_type::total
697 */
698 template <
699 BOOST_ASIO_COMPLETION_TOKEN_FOR(void (boost::system::error_code))
700 WaitToken = default_completion_token_t<executor_type>>
701 auto async_wait(wait_type w,
702 WaitToken&& token = default_completion_token_t<executor_type>())
703 -> decltype(
704 async_initiate<WaitToken, void (boost::system::error_code)>(
705 declval<initiate_async_wait>(), token, w))
706 {
707 return async_initiate<WaitToken, void (boost::system::error_code)>(
708 initiate_async_wait(this), token, w);
709 }
710
711protected:
712 /// Protected destructor to prevent deletion through this type.
713 /**
714 * This function destroys the descriptor, cancelling any outstanding
715 * asynchronous wait operations associated with the descriptor as if by
716 * calling @c cancel.
717 */
718 ~basic_descriptor()
719 {
720 }
721
722#if defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
723 detail::io_object_impl<detail::io_uring_descriptor_service, Executor> impl_;
724#else // defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
725 detail::io_object_impl<detail::reactive_descriptor_service, Executor> impl_;
726#endif // defined(BOOST_ASIO_HAS_IO_URING_AS_DEFAULT)
727
728private:
729 // Disallow copying and assignment.
730 basic_descriptor(const basic_descriptor&) = delete;
731 basic_descriptor& operator=(const basic_descriptor&) = delete;
732
733 class initiate_async_wait
734 {
735 public:
736 typedef Executor executor_type;
737
738 explicit initiate_async_wait(basic_descriptor* self)
739 : self_(self)
740 {
741 }
742
743 const executor_type& get_executor() const noexcept
744 {
745 return self_->get_executor();
746 }
747
748 template <typename WaitHandler>
749 void operator()(WaitHandler&& handler, wait_type w) const
750 {
751 // If you get an error on the following line it means that your handler
752 // does not meet the documented type requirements for a WaitHandler.
753 BOOST_ASIO_WAIT_HANDLER_CHECK(WaitHandler, handler) type_check;
754
755 detail::non_const_lvalue<WaitHandler> handler2(handler);
756 self_->impl_.get_service().async_wait(
757 self_->impl_.get_implementation(), w,
758 handler2.value, self_->impl_.get_executor());
759 }
760
761 private:
762 basic_descriptor* self_;
763 };
764};
765
766} // namespace posix
767} // namespace asio
768} // namespace boost
769
770#include <boost/asio/detail/pop_options.hpp>
771
772#endif // defined(BOOST_ASIO_HAS_POSIX_STREAM_DESCRIPTOR)
773 // || defined(GENERATING_DOCUMENTATION)
774
775#endif // BOOST_ASIO_POSIX_BASIC_DESCRIPTOR_HPP
776

source code of boost/libs/asio/include/boost/asio/posix/basic_descriptor.hpp